The present invention relates to an arrangement of bearings for an open-end spinning rotor of an open-end spinning device which is radially supported with its shaft in the nip of supporting rings and which bears on an axial bearing. From EP 0 435 016 A2 and also from DE 40 22 562 A1, such an arrangement of bearings is known. To produce the axial thrust, the axes of the supporting rollers are in a known manner not parallel with the rotor shaft but are placed at an angle to it, as is known for example from DE-A 21 12 913. In other arrangements of bearings known from DE-A 20 61 520 and DE-A 19 01 453, the axial thrust on the rotor shaft is produced in that the driving device, e.g. a tangential belt or a drive wheel, is installed at an angle relative to the axis of the rotor shaft.
It is a disadvantage of the known arrangements of bearings that a great expenditure of energy is required to operate them and that the operation causes great wear on the supporting rings and on the rotor shaft. A considerable portion of the energy consumption of such an arrangement of bearings is caused by the coiling conditions of the rotor shaft on the supporting rings. The production of the axial thrust by the supporting rings or the driving device causes slip between these and the rotor shaft. The state of the art, with respect of determining the axial thrust, has assumed that the rotor shaft bears upon a step bearing which constitutes a fixed support. Such a fixed support is shown for example in DE-A 21 12 913 or also in U.S. Pat. No. 4,916,891, where the support of the rotor shaft is effected by means of a ball against which the rotor shaft bears. This results in wear of the ball and shaft. With such axial arrangements of bearings in combination with the production of the axial thrust on the spinning rotor by means of the bearing elements or the driving device, the danger exists that axial oscillations of the rotor shaft due to the hard, elastic support at the axial bearing cause the rotor to leave its position and to run up against the cover of its rotor housing. In order to prevent this, the state of the art has seen to it, through a relatively sharp angle position of the supporting ring axes or of the driving device or through strong pressure of the rotor shaft against the supporting rings, e.g. by means of the driving devices or through appropriate sizing of the supporting rings and of the rotor shaft, that a strong axial thrust is exerted in the direction of the axial bearing upon the rotor shaft, so that the spinning rotor maintains its axial position. As a result, the crossing of the supporting rings in combination with the contact pressure of the driving device and the laying conditions of the rotor shaft in the nip of the supporting rings, as well as the frictional conditions between the supporting rings or driving device and the rotor shaft, has led to axial thrusts of over 8N. This value constitutes the measure of energy consumption which applies in addition to normal bearing friction.